The pay between the pay of top chief executives and the staff they manage appears to be growing.

In the latest Fairfax annual survey of pay rates at listed companies, the average pay of CEOs in 2012 was 26.4 times that of the average employee in the same companies. That's up from a multiple of 22.5 times in 2011.

The survey covered 39 companies on the NZX50, of which 23 had consistent data available for the last three years. Investment companies and dual listed Australian companies were excluded because their pay structures were not readily comparable.

Of the 23 companies comparable over time, 17 paid their CEO more in 2012 than the previous year. Average staff pay, estimated by dividing each company's total pay bill by the number of its staff, increased at 16. However, pay rises for staff were on average lower than those for CEOs.

Oliver Hartwich, executive director of business research and lobby group the New Zealand Initiative, said the causes of the pay trend were obscure although it appeared to be a global phenomenon.

"On the other hand what I always hear from businesses in New Zealand is there is a lack of talent in the country generally, and it's probably difficult to find the right people to head companies so that's probably driving up salaries at the top end of the market."

Hartwich said there was academic evidence indicating the skill of a CEO was important in company performance.

"It's one of the major factors driving success of companies long term."

Nevertheless, there was a level where top pay became excessive.

"Once the top is so far removed from the rest of the company and they're being paid in the eyes of the ordinary employees almost regardless of what they do, then the company's got a problem and it's difficult to motivate your staff," he said. "I don't think we've reached that point in New Zealand yet."

There was no doubt that employee motivation was affected by perceptions of fairness, said Hartwich.

"I think people in top management have to be able to make the case why they should be paid that much."

Bill Rosenberg, economist for the Council of Trade Unions, said although the pay gap was smaller in New Zealand than in the US, it was already a matter of concern.

"A lot of people working in New Zealand would look at those [numbers] with some disgust actually," he said. "Their pay is only crawling up and yet you see continuing much higher increases for the CEOs and that gap widening.

"It's not as if people aren't working hard and contributing to those companies. It's actually very difficult to distinguish who contributes most to the productivity of the company, whether it's someone working away at their job or whether it's the CEO."

Data compiled by Bloomberg from 250 companies in the US S&P500 index found the average multiple of CEO pay to that of rank-and-file workers in 2011/12 was 204, up 20 per cent since 2009.

The highest multiple was 1795 for retailer JC Penney, where the CEO was paid US$53.1m. The lowest was 173 for Agilent Technologies, whose CEO was

paid US$10.1M.

The data will be easier to compile from now on because on September 18 the US Securities & Exchange Commission implemented a new disclosure rule required by the Dodd-Frank Act. The rule requires public companies to disclose the median annual pay of their employees, the total annual pay of the CEO and the ratio of the two.

It's a controversial measure, not least because the ratio is affected by the pay rates in particular industries. Workers in retail or fast food for example are paid less than those in it or pharmaceuticals, so the CEO pay multiples appear larger.

The data in the Star-Times survey show the same pattern. Companies in retail, aged care and fast food - Restaurant Brands, Ryman Healthcare, Pumpkin Patch, Warehouse Group and Kathmandu - had the lowest average staff cost, which tended to place their CEO pay multiples at the upper end of the range. Their CEO pay multiples ranged from 27.4 times for Ryman and 52.6 times for Restaurant Brands.

The highest pay multiple in the survey was at casino operator Skycity Entertainment Group, whose CEO Nigel Morrison was paid 70.9 times as much as the average employee. The high multiple reflects the relatively low pay oF casino staff alongside the relatively high pay of Morrison, whose $2.9m remuneration was the fourth highest of listed companies surveyed.

Companies with the highest average staff cost - NZ Refining, Telecom, Air New Zealand, Xero and Nuplex - included some of the lowest CEO pay multiples in the survey with Xero, on 2.6, and NZ Refining on 7.

Those figures should be no surprise as pay rates in the oil and gas industry are among the highest in the country, while knowledge workers in IT can also command good salaries.

Another software company, Trade Me, had the third lowest pay multiple of 8.2.

The wide range of pay multiples suggests there is no single number that can be regarded as appropriate across the board, although the Australian Council of Trade Unions resolved in 2009 to seek a legal cap on the base pay of CEOs at 10 times the average earnings in the same enterprise.

Hartwich does not favour regulatory intervention, preferring to see shareholders take responsibility for rewarding their executives.

"If shareholders owning the company can have the final say in how much they want to pay their management that's a good idea. But the obvious problem is getting shareholders involved. When you look at the number of shareholders attending meetings, it's quite discouraging actually."